Portable, air-operated, magazine-fed nailing machine



3 Sheets-Sheet 1 H. R. FISCHER ETAL PORTABLE, AIR-OPERATED, MAGAZINE-FEDNAILING MACHINE w NdHl l hhhhl l HHHHHu l H 2 FIL E m March 6, 1962Filed June 21, 1960 INVENTORSI 661444190 A. HJCl/E/P (X40455 A.Foes/P219 y m ATTORNEY FIG. I

March 6, 1962 H. R. FISCHER ETAL 3,023,413

PORTABLE, AIR-0PERATED, MAGAZINE-FED NAILING MACHINE Filed June 21, 19603 Sheets-Sheet 5 United States Patent M ,023,4 3. PORTABLE, I -OPERATED,MAGAZINE-FED NAILING MACHINE Howard R. Fischer and James A. Roberts,Utica, N.Y., assignors to Chicago Pneumatic Tool Company, New York, acorporation of New Jersey FiledJune 21, 1960, Ser. No. 37,700 Claims.(Cl.- 1-44.4)

a driving blade assembly that strips the individual nail from the bondednail strip, advances the nail to the surface of the work piece, has itshammering action automatically started thereupon and continues to beadvanced as the nail is driven.

It is still another object of the invention to provide an air-operated,magazinefed, nailing machine that has an automatic control valve on thefeed piston for controlling the operation of the hammer piston inresponse to the build up of air pressure against the feed piston whenthe nail point has engaged the workpiece.

It is still another object of the invention to provide a portable,air-operated, magazine-fed nailing machine in which a combined feedpiston and hammer assembly is fully enclosed by. the machine body andthemachine body serves as a connecting member for the support of theother component parts of the machine, whereby ofv the parts of themachine will be contained in one housing body.

It is a further object of the invention to provide in an air-operated,magazine-fed nailing machine in which the cycle. of operation of. themachine is started by a trigger-operated air valve, an adjustable cutoffvalve that will automatically stop the machine when the nail has beendriven to its full extent or to a predetermined distance into the work.

It is still a further, object of the invention to provide an air-operatd, magazine-fed nailing, machine in hen the anvil is slidably retainedin a bushing within the feed piston structure and i s cushioned in itsblow and returned against the sleeve. by rubber ring cushioning meansfixed in the lower end of the feed piston structure.

Other objects of the invention are. to provide an airoperated,magazine-fed nailing machine, having the above objects in mind, which isof simple construction, has a minimum number of parts, is compact, lightin weight, easy to load, maintain and handle, efficient and effective inuse, and automatic in operation.

For a better understanding of the invention, reference m ybe had to thefollowing detailed construction taken in connection withthe accompanyingdrawing, in which FIGURE 1 is a vertical sectional view taken through.the nailing machine of the present invention with the feed pistonstructure and the driving blade retracted,

FIG. 2 is an enlarged vertical sectional view of the top of the machineangled from the vertical section of F G- FIG. 3 is an enlargedfragmentary, vertical sectional view of the intermediate part of thenailing machine similar in section to FIG. 2, with the feeding pistonadvanced 3,023,413 Patented Mar. 6, 1962 to place the hammerintooperation and with the hammer resting upon the anvil,

FIG. 4 is an enlarged fragmentary vertical sectional View of the hammerexhaust control passage, similar in section to FIG. 3,

FIG. 5v is. a vertical sectional view of the nailer body and of the feedpiston structure in full advanced to locate the. point of the nail uponthe work surface, preparatory to the hammering action being effected,

FIG. 6 is a transverse sectional view of the nailing machine lookingupon the top surface of the air distributing plate and as'viewed on line6-6 of FIG. 1

FIG. 7 is an enlarged transverse sectional view of the nailing machine,taken just below the distributing plate and looking upon the laterallyshiftable valve ring and into the air supply and exhaust passages oftheffeed piston structure that serve to supply and exhaust air from thehammer piston chamber therewithin, and as viewed on line 7-7 of FIG. 1,

FIG. 8 is a transverse sectional view of the nailing machine at theupper end'thereof and taken through the feed piston andthe automaticvalve for controlling the supply of air to the hammer piston cylinder,the view being taken on line 88 of FIG, 2,

FIG. 9 is a transverse sectional view of the nailing machine at thelower end thereof and taken through the driving blade and the automaticcutoff mechanism, and more particularly upon line 9 9 of FIG. 1, I

FIG. 10 is an enlarged fragmentary vertical sectional View looking upon:the trigger operated air supply valve within the handle and the cutoffvalve mechanism, the cutoff valve being in its closed position, and

FIG. U is an enlarged fragmentary vertical sectional view similar toFIG. 10 butwith the cutoff valve mechanism having been operated by thefeed piston, and the cutoff valve being in its open position.

Referring now to the figures, 15 represents a nailer body in which thereis a cylindrical chamber 16 and extending laterally from the body is avalve handle 17. On the lower end of the nailer body 15 is a footportion 18 to the underside of which there is fixed a nail magazineassembly 19. A driving blade guidejZ O; having 'a guide slot 21 isconnected to the magazine by fastening bolts 22 and 23. Nails N areT-shaped and are bonded together to provide nail strips that can besupported on a guideway 24 within the magazine 19. A nail strip follower25 urges the nail strip toward the blade guide 20 so that theforwardmost nail is delivered to the guide slot '21. The nail follower25 is forced forwardly by a long tension spring 27 that is connected tothe follower and extended over a forward pulley 28 and anchored to aprojection 29 at the rear end of the magazine.

To insert the nails into the magazine, the follower 25 is pulledrearwardly and held in its rearward position by raising a catch lock 30into recess 31 in the magazine housing. A door 32 is provided on the topof the maganine and when it is opened a nail strip may be loaded intothe magazine. These nails are vertically supported upon the guideway 24-by their heads and held against lateral displacement by side guideplates 33 and while being fed by the long tension spring 27 to the driveguide slot 21. When the door is closed,'the follower 25fis released andpushes the leading nail of the strip into slot 21 under a driving blade34.

Upon the upper end of the mailer body 15 over the cylindrical chamber16;, there is secured by means of screw bolts 37 a reduced diameter feedpiston chamber extension cap 36 which serves as one hand grip for themachine. Slidable in the cylindrical chamber 1 6, is a feed pistonstructure 38 that has a small diameter upwardly-extending integralsleeve extension 39 that extends into a reduced diameter cylinderextension 41 provided by the cap 36. Sealing rings 40 are provided onthe extension 39 to hold down air leakage to the main portion of thefeed piston chamber 16. This piston sleeve extension 39 has a centralpassage 42 depending from its upper end into a valve chamber 43' whichis closed from the depending passage 42 by an inverted cup-shapedautomatic hammer control valve 44 supported in its closed position by acompression spring 45 resting upon an air distributor plate 47 that isrestrained therewithin the feed piston structure 38 by a dependingpiston skirt 48 that is threaded tightly thereinto against the airdistributor plate 47 to support the distributor plate therewithin.

The upper end of the piston skirt 48' is relieved at the opposite sidesto provide an elliptical projection 49 that is surrounded by a ringvalve 51 laterally shiftable within side spaces 52 afiorded by theelliptical shape of the projection 49. This ring valve mechanism hasbeen described in detail in the Edward W. Stevens Patents 1,860,964granted May 31, 1932 and 1,931,041 granted October 17, 1933 whereby acutaway of the opposite sides provide an elliptical transverse shape ofthe projection 49, so that the ring valve 51 can move laterally first toclose ports 53 in one side of the projection 49 and then ports 54 in theother side of the projection 49'.

The ring valve 51 alternatively shifts first to one side and then to theother depending upon the direction to which a hammer piston 56 is to bemoved within a piston chamber 57. A key 59 holds the piston skirt 48against being unthreaded from the piston structure 38 and the airdistributor plate 47 in place. The piston skirt 48 has a long key Way 61that receives a key 62 projected inwardly from the nailer body 15 tohold the piston structure 38 against rotation while being Worked. Thefeed piston is biased to its raised position by a return compressionspring 63 that engages the underside of the piston structure 38. Thisspring 63 surrounds the piston skirt 48 and reacts between a shoulder 64in the lower end of the nailer body 15 and a shoulder 65 on the pistonskirt 48. The driving blade 34 is fixed to an enlarged lower end 66 ofan anvil 67 that is slidably carried in a sleeve bushing 68 tightlyfitted upwardly in the piston skirt 48 against an internal shoulder 69.

In the lower end of the piston skirt 48, FIGS. 1 and 3, there isprovided cushioning means for the anvil 67 comprising a bottom retainingring 71 fixed by two pins 72 and 73 to the lower end of the piston skirt48 that supports a rubber cushioning ring 74 and a metal wear ring 76thereabove. The driving blade 34 extends downwardly from the enlargedend 66 of the anvil through these rings and between the pins 72 and 73and into the drive guide nail dispensing slot 21. The anvil 67 isbounced by the cushioning means after a hammer blow into the sleevebushing 68 and limited in its upward movement by the engagement of theenlarged end 66 of the anvil with the lower end of the sleeve bushing68.

In the valve handle 17 is a valve opening 77, FIG. 10. to which an airhose fitting 78 is threadedly connected. This hose fitting 78 has avalve compression spring 79 seated therein that normally holds a valveassembly 81 the closed position upon the end of the sleeve 82, FIG. 1,to prevent the passage of air through the valve bushing 82. The valveassembly 81 has a guide stem 83 that is slidable in the valve bushing 82and is adapted to cover when the valve 81 is lifted from its seat, anexhaust port 84 in the sleeve 82, FIG. 10. This port 84 communicateswith an exhaust passage 86 that exhausts air through the rear end of thehandle to the atmosphere. The valve guide stem 83 has a reduced diameterportion 87. Upon the valve 81 being released forwardly into the closedposition upon the end of the sleeve 82, FIG. 1, air from the machine canbe returned through a port 91 on the upper side of the sleeve 82 alongthe reduced 4 diameter portion 87 of the valve stem, through the port 84and be exhausted through the handle passage 86.

A trigger-operated arm 92 is pivoted Within a recess 93, extendingupwardly from the underside of the valve handle 17, by a pivot pin 94and engages the forward end of the valve guide stem 83 to open the valve81 when a trigger plunger 96 is pulled upwardly by a finger whilegrasping the handle 17. The trigger plunger carries a rounded end 97 ofthe pivot arm 92. to pivot the same, and cause its nose end 97' toengage the end of the stem 83 and the valve 81 to be lifted from itsseat against the action of the compression spring 79, FIG. 10. Theexhaust port 84 in the sleeve 82 will be closed by the valve stem 83 andair entering the fitting 78 passes the valve 81, the sleeve port 91 andinto an air supply passage 98 running through the full extent of thehandle. The drillings for this passage 98 are closed by plugs 99 and101, one of these drillings leading from the valve sleeve port 91.

Within the inner part of the handle 17, is a verticallyextending opening103 that has a vertically-extending valve bushing 104 tightly fittedtherein. A cutofi. valve plunger 105 operates in the valve bushing 104and is held down by along compression spring 106 reacting against a stopplug 107 secured in the upper end of the opening 103 by a sleeve pin 107and against the upper end of a push rod 108. The push rod 108 extendsdownwardly through a depending reduced diameter extension 109 of thevalve bushing 104 and is held in place against downward displacement bya stop pin 110 in the extension 109 and engaging the upper end of anelongated step recess 111 in the side of the push rod 108. The upwardmovement of push rod 108 is limited by the same stop pin 110 upon beingengaged by the push rod at the lower end of the elongated recess 111.

When the cutoif valve plunger 105 is held down by its compression spring106 it is supported upon the push rod 108 and air from the supplypassage 98 passes through a port 112 in the valve bushing 104, aboutannular groove 113 in the plunger valve 105, a port 114 in the oppositeside of the valve bushing 105 to a transverse passage 115 in the nailerbody 15 and upwardly through a vertical passage 116 to the top thereof.This passage 116 communicates past a sealing ring 116' with a passage117 in the extension cap 36 extending upwardly in continuation from thepassage 116 and through a top port 118 into the feed piston chamberextension 41. The drillings providing the passage 117 and the port 118are closed respectively by stop plugs 119 and 120 welded thereinto.

Air entering the the central passage 42 in the piston sleeve extension39 exerts a downard pressure against the seated valve 44. This pressureis at this time insufiicent to overcome the resistance of the valve 45,so that the valve remains seated and the pressure of the air acting uponthe valve 44 forces down the piston structure 38 to place the pointedend of the nail N in contact with the work piece, FIG. 5, and continuesthe downward movement of the feed piston 38 to maintain the hammeringaction of the hammer piston upon the nail until it is driven. Since thesmall hammer piston 56 is within the piston structure 38, both pistonsare advanced. The downard movement of feed piston structure 38 isagainst the action of the return spring 63. The downward motion of thefeed piston structure forces the driving blade 34 through the guide slot21 and strips the first nail from the bonded strip of nails and pushesthe nail downwardly into contact with the work piece. The nail is heldin the vertical position in the guide slot 21 by the pressure from thesucceeding nail of the bonded nail strip and the long magazine tensionspring 27.

When the nail point contacts the work piece surface, however, greaterresistance is encountered and the air pressure is built up in thecylindrical chamber 16 above the feed piston structure 38 and in thecentral piston passage 42 of the piston feed extension 39 to open theham mer control valve 44 against the action of the compression spring 45and allow the air to enter the valve chamber 43 (FIG. 3). The controlvalve chamber 43 has four radially-extending ports 122 from the outerends of which the air passes downwardly through respective verticalpassages 123 into an annular recess in the top of the air distributingplate 47. The air distributing plate 47, in turn has fourradially-extending passages 126 leading outwardly into respectivevertical notches 127 in the outer periphery of the distributing plate 47whereby air will be distributed to the opposite sides of the pistonstructure 38 and into the spaces 52 at the opposite sides of theupstanding elliptical projection 49 on piston skirt 48 in which the ringvalve 51 is shifted. The ring valve 51 moves laterally to alternatelysupply air to the opposite ends of the hammer piston chamber 57 andthereby causes the reciprocation of the hammer piston 56.

Air passes valve 51 and inwardly through ports 53 and downwardly throughpassages 128 at the one side of the piston skirt 48 and inwardly throughthe ports 129 into the hammer piston chamber 57 to lift the hammerpiston 56. Vertical exhaust passages 132 have vertically spaced ports133 and 134 and an intermediate exhaust port 135 by which the exhaustair passes into the cylindrical chamber 16 of the nailer body 15 andoutwardly through an exhaust port 136 thereof to the atmosphere.

The hammer piston 56 thus serves as its own valve to reverse the flow ofair to the opposite sides of the hammer piston to obtain thereciprocation thereof. As the hammer piston 56 is lifted, the exhaustport 133 is closed by the piston itself and the lower exhaust port 134is opened. The air above the hammer piston 56 is compressed sufiicientlyto displace ring valve 51 from the ports 54 and allow the air then topass from the ring space 52 through the ports 54 into the top of thehammer chamber 57 and reverse the movement of the hammer 56 so as todeliver a blow upon the anvil 67. The cycle of operation isautomatically continued so that a series of blows are delivered to theanvil to drive the nail N. The hammer blows are transmitted from theanvil to the driving blade 34 and the entire piston structure advancesdownwardly as the nail is driven since pressure continues to be exertedon the top of the piston structure 38.

When the feed piston structure 38 is advanced downward to a point wherethe lower end of the piston skirt 48 contacts a cutoff valve actuator141 lying in a slot 140 in the depending foot portion 18 of the nailerbody 15, FIGS. 1, 5, and 11, the cutoff actuator 141 is pivoted on a pin142 to the position shown in FIG. 11. On a threaded lower end 143 of thepush rod 108 is an adjustable nut 144 with which the actuator engages.The downward movement of the feed piston 38 thus causes the opposite endof the actuator 141 to rise and engage with the adjustable nut 144 whichin turn forces the push rod 108 and cutoff valve 105 upwardly againstthe action of the valve compression spring 106 until a passage 145 inthe sleeve bushing 104 is exposed, FIG. 11. At this point air from thesupply passage 98 enters the bushing 104 through the passage 145, takesover and forces the cutoif valve 105 up against a stop plate 146, O-ring147 and the stop plug 107. Some of the air entering the sleeve bushing104 beneath the cutoff valve 105 bleeds through a hole 149 in the valve105 and outwardly through a hole 151 in the stop plug 107 to atmosphere.Since the passage 145 passes more air than the hole 149, the cutoffvalve 105 remains in its raised position so long as the valve 81 is keptopen by the trigger 96. In this position, the valve 105 closes thebushing port 11 4 to cutoff the flow of air to the feed piston chamber16, air is then trapped in the passages 115 and 116 in the nailer body15, and in the feed piston chamber 16 and the hammer piston chamber 57.The hammer piston 56 delivers one or two more blows until enough airescapes through the hammer exhaust ports 135 and 136 to lower thepressure in the central passage 42 sufliciently to permit the spring 45to force the control valve 44 upwardly into engagement with its seat toclose off the valve chamber 43 from the central passage 42 in the pistonextension 39. At this point the hammer 56 ceases to operate. The pistonstructure 38 is returned by compression return spring 63 as the trappedair leaves through the exhaust passage 152 in the extension cap 36.

Due to the threaded connection between the adjusting nut 144 and thecutoff valve push rod 108, the point at which the cutoff valve is closedcan be adjusted and the point of travel of the driving blade 34 at whichthe hammering stops and the blade ceases to be effective. Thus, byadjusting this nut 144 upon the push rod the nail heads can be drivenflush with the work surface, countersunk from the work surface or leftprojected slightly above the work surface.

When the trigger 96 is manually released the valve 81 is closed by itsspring 79 and the air is exhausted through the handle passage 86. Thespring 106 forces the cutoff valve down until it contacts the push rod108 which has been held in its raised position by the actuator 141. Thefeed piston 38 is raised and the actuator 141 then permits the push rod108 to drop and the control valve 105 returned to its lowered positionso that the nailing machine is made ready for the next cycle ofoperation.

It should be apparent that there has been provided an effectiveautomatic control valve to control the operation of the hammer piston inresponse to the delivery of the nail to the work piece by the feedpiston structure and an equally effective adjustable cutoff mechanismfor automatically stopping the operation of the machine when the nailhas been driven.

While various changes may be made in the detailed construction it shallbe understood that such changes shall be within the spirit and scope ofthe present invention as defined by the appended claims.

What is claimed is:

1. In an air-operated, magazine-fed nailing machine, a nailer bodyhaving a feed piston chamber therein, air supply passages extending tothe top of the feed piston chamber, a feed piston structure operable insaid feed piston chamber, a return spring in the feed piston chamber forbiasing the feed piston to its retracted position, said feed pistonstructure having a hammer piston chamber therein, a hammer pistonoperable in the hammer piston chamber, an anvil in the hammer pistonchamber adapted to be actuated by the hammer piston, 21 driver bladedepending from the anvil and the feed piston structure, valve mechanismfor operating the hammer piston, a magazine for feeding nail strips, adriver blade guide connected to the magazine and having a guide slot forreceiving the driver blade and the nail from the maga- Zine, anair-operated control valve on the feed piston structure operable inresponse to the resistance of the nail upon the work to supply the airto the hammer piston valve mechanism, whereby upon air being extended tothe feed piston chamber the nail is advanced so that its point engagesthe work surface before the hammering action is effected by the openingof the control valve, and means responsive to a predetermined movementof the feed piston structure to shut off flow of air to the said airsupply passages.

2. In an air-operated, magazine-fed nailing machine, a nailer bodyhaving a feed piston chamber therein, air supply passages extending tothe top of the feed piston chamber, a feed piston structure operable insaid feed piston chamber, a return spring in the feed piston chamber forbiasing the feed piston to its retracted position, said feed pistonstructure having a hammer piston chamber therein, a hammer pistonoperable in the hammer piston chamber, an anvil in the hammer pistonchamber adapted to be engaged by the hammer piston, a driver bladedepending from the anvil and the feed piston structure, valve mechanismfor operating the hammer piston,

a magazine for feeding nail strips, a blade guide. connected to themagazine and having a guide slot for receiving the driver blade and thenail from the magazine, an air operated control valve on the feed pistonstructure operable in response to the resistance of the nail upon thework to supply the air to the hammer piston valve mechanism, said feedpiston structure having a reduced diameter extension and said nailerbody having a reduced diameter chamber extension for receiving thepiston extension, said piston extension having a central passagedepending from its upper end thereof to said hammer supply control valveso that the air that advances the feed piston has access to the controlvalve, a spring biasing said control valve upwardly into its closedposition, whereby upon air being extended to the feed piston chamber thenail is advanced so that its point engages the work surface before thehammering action is effected by the opening of the control valve, andmeans responsive to a predetermined movement of the feed piston to shutoff flow of air to the said air supply passages.

3. In an air-operated, magazine-fed nailing machine, a nailer bodyhaving a feed piston chamber therein and a laterally-extending handleportion, air supply passages extending from the handle portion to thetop of the feed piston chamber, a feed piston structure operable in saidfeed piston chamber, a return spring in the feed piston chamber forbiasing the feed piston to its retracted position, said feed pistonstructure having a hammer piston chamber therein, a hammer pistonoperable in the hammer piston chamber, an anvil in the hammer pistonchamber adapted to be engaged by the hammer piston, a driver bladedepending from the anvil and the feed piston structure, valve mechanismfor operating the hammer piston, a magazine for feeding nail strips, ablade guide connected to the magazine and having a guide slot forreceiving the driver blade and the nail from the magazine, anair-operated control valve on the feed piston structure operable inresponse to the resistance of the nail upon the work to supply the airto the hammer piston valve mechanism, a cutoff valve mechanism in theair supply passages of the handle portion, a depending push rod foroperating said cutoff mechanism, and an actuator carried on the nailerbody and engageable by said feed piston structure and engaging said pushrod upon the nail having been driven a predetermined distance into thework piece, whereby upon air being extended to the feed piston chamberthe nail is advanced so that its point engages the work surface beforethe hammering action is effected by the opening of the control valve andthe machine automatically stopped when the nail has been driven.

4. In an air-operated, magazine-fed nailing machine, a nailer bodyhaving a feed piston chamber therein and a laterally-extending handleportion, air supply passages extending from the handle portion to thetop of the feed piston chamber, a feed piston structure operable in saidfeed piston chamber, a return spring in the feed piston chamber forbiasing the feed piston to its retracted position, said feed pistonstructure having a hammer piston chamber therein, a hammer pistonoperable in the hammer piston chamber, an anvil in the hammer pistonchamber adapted to be engaged by the hammer piston, a driver bladedepending from the anvil and the feed piston structure, valve mechanismfor operating the hammer piston, a magazine for feeding nail strips, ablade guide connected to the magazine and having a guide slot forreceiving the driver blade and the nail from the magazine, anair-operated control valve on the feed piston structure operable inresponse to the resistance of the nail upon the work to supply the airto the hammer piston valve mechanism, a cutoff valve mechanism in theair supply passages of handle portion, a depending push rod foroperating said cutofi mechanism, and an actuator carried on the nailerbody and engageable by said feed piston structure and engaging said pushrod upon the nail 8 having been driven a predetermined distance into theWork piece, and said nailer body having a foot portion extendinglaterally therefrom, said foot portion having a slot therein leadingfrom the body chamber, said actuator extending into the body chamber tobe actuated by the feed piston and pivoted within said slot, and saidpush rod having an adjustable nut thereon and engageable by the outerend of said pivoted actuator, whereby upon air being extended to thefeed piston chamber the nail is advanced so that its point engages thework surface before the hammering action is effected by the opening ofthe control valve and the machine automatically stopped when the nailhas been driven.

5. In an air-operated magazine-fed nailing machine as defined in claim3, said cutoff valve being vertically movable and normally spring biasedtoward said push rod, an air passage leading from the one of said airsupply passages and normally closed by the cutoff valve, said push rodwhen lifted by the actuator adapted to lift the cutoff valve above theair passage to let air entering the valve opening complete the liftingof the cutoff valve, and air exhaust passages leading through the cutoffvalve and the handle portion to the atmosphere, said cutoff valve airpassage passing more air than the cutoff valve exhaust passages wherebyto sustain the cutoff valve in its lifted position until air supply isshut off.

6. In an air-operated, magazine-fed nailing machine, a nailer bodyhaving a feed piston chamber therein, air supply passages extending tothe top of the feed piston chamber, a feed piston structure operable insaid feed piston chamber, a return spring in the feed piston chamber forbiasing the feed piston to its retracted position, said feed pistonstructure having a hammer piston chamber therein, a hammer pistonoperable in the hammer piston chamber, an anvil in the hammer pistonchamber adapted to be actuated by the hammer piston, a driver bladedepending from the anvil and the feed piston structure, the pistonstructure, hammer piston, anvil, and driver blade having a commonlongitudinal axis, valve mechanism for operating the hammer piston, amagazine for feeding nail strips, a driver blade guide connected to themagazine and having a guide slot for receiving the driver blade and thenail from the magazine, and an air-operated control valve on the feedpiston structure operable in response to the resistance of the nail uponthe work to supply the air to the hammer piston valve mechanism, andhammer valve mechanism on the piston structure including an airdistributor plate and a piston skirt retained within the pistonstructure, said piston skirt having a projection providing spaces at theopposite sides thereof, a laterally shiftable ring valve shiftable uponthe projection, and supply ports running through the piston skirt tofeed air to the upper and lower sides of the hammer piston chamber, andexhaust port means in the piston skirt and operable by said hammerpiston and in cooperation with the ring valve to effect thereciprocation of the hammer piston, whereby upon air being extended tothe feed piston chamber the nail is advanced so that its point engagesthe work surface before the hamering action is effected by the openingof the control valve.

7. In an air-operated, magazine-fed nailing machine, a nailer bodyhaving a feed piston chamber and a laterally-extending handle portion,air supply passages extending from the handle portion to the top of thefeed piston chamber, a feed piston structure operable in said feedpiston chamber, a return spring in the feed piston chamber for biasingthe feed piston to its retracted position, said feed piston structurehaving a hammer piston chamber therein, a hammer piston operable in thehammer piston chamber, an anvil in the hammer piston chamber adapted tobe engaged by the hammer piston, a driver blade depending from the anviland the feed piston structure, valve mechanism for operating the hammerpiston, a magazine for feeding nail strips, a

blade guide connected to the magazine and having a guide slot forreceiving the driver blade and the nail from the magazine, and an airoperated control valve on the feed piston structure operable in responseto the resistance of the nail upon the work to supply the air to thehammer piston valve mechanism, said feed piston structure having areduced diameter extension and said nailer body having a reduceddiameter chamber extension for receiving the piston extension, saidpiston extension having a central passage depending from its upper endthereof to said hammer supply control valve so that the air thatadvances the feed piston has access to the control valve, and a springbiasing said control valve upwardly into its closed position, said airsupply passages extending through the handle portion, the mailer bodyand the reduced-diameter chamber extension, a control valve in thehandle air passage, a trigger means for operating the air control valveprovided on the handle portion and cut on valve means in said handlepassage and operable by the feed piston structure when the nail has beendriven a predetermined distance, whereby upon air being extended to thefeed piston chamber the nail is advanced so that its point engages thework surface before the hammering action is effected by the opening ofthe control valve.

8. In an air-operated, magazine-fed nailing machine, a mailer bodyhaving a feed piston chamber therein, air supply passages extending tothe top of the feed piston chamber, a feed piston structure operable insaid feed piston chamber, a return spring in the feed piston chamber forbiasing the feed piston to its retracted position, said feed pistonstructure having a hammer piston chamber therein, a hammer pistonoperable in the hammer piston chamber, an anvil in the hammer pistonchamber adapted to be engaged by the hammer piston, a driver bladedepending from the anvil and the feed piston structure, valve mechanismfor operating the hammer piston, a magazine for feeding nail strips, ablade guide connected to the magazine and having a guide slot forreceiving the driver blade and the nail from the magazine, anair-operated control valve on the feed piston structure operable inresponse to the resistance of the nail upon the work to supply the airto the hammer piston valve mechanism, said piston structure including adepending skirt, a vertically-extending bushing retained in said pistonskirt against upward displacement, said anvil being vertically slidablein said bushing, said anvil having an enlarged bottom head andengageable with the lower end of said bushing to limit its upwardmovement, said driver blade depending from the enlarged bottom head ofthe anvil, an annular retaining ring fixed within the lower end of thedepending piston skirt, cushioning ring means supported by saidretaining ring and engageable by the enlarged bottom head of the anvilto cushion the blow and return the anvil preparatory to the next blow,whereby upon air being extended to the feed piston chamber the nail isadvanced so that its point engages the work surface before the hammeringaction is effected by the opening of the control valve, and air out offmeans in the air supply passages actuable by the skirt of the pistonstructure to shut off flow of air through said passages upon the pistonstructure moving a predetermined distance in the direction of the nail.

9. In a fluid powered nailing machine including a housing having a mainpiston chamber, a main piston operable in this chamber and carrying anail driver element for engagement with a nail that is to be driven intoa workpiece, a return spring biasing the main piston to a returnedinitial position, a piston cylinder defined within the main piston, thedriver element having an upper portion thereof in the lower end of thepiston cylinder, a hammer piston reciprocable in the piston cylinder forpounding the said upper portion of the driver element, and valvemechanism for alternately applying operating pressure fluid to oppositeends of the piston cylinder to reciprocate the hammer piston; controlmeans initially causing pressure fluid to be applied to the main pistonto move the latter against the spring so as to carry the driver elementagainst the nail to be driven, and for subsequently causing in responseto a predetermined resistance of the nail to the driven ele-' mentpressure fluid to be applied simultaneously to the main piston to pressthe driver element continuously against the nail and to be applied tothe valve means to effect reciprocation of the hammer piston, and airshut ofl? means responsive to a predetermined movement of the driverelement subsequent to its engagement with the nail to cut off the flowof pressure fluid to the machine.

10. In a fluid powered machine for driving a rigid linear element intoan object, including a main piston carrying a driving member for drivingthe rigid element, the main piston being movable to carry the drivingmember linearly into abutment with the rigid element, a reciprocablehammer piston for pounding the driving member; means for initiallycausing pressure fluid to be applied to the main piston to carry thedriving member into abutment with the rigid element, and forsubsequently acting in response to a predetermined resistance of therigid element to the driving member to cause operating pressure fluid tobe applied to the main piston to hold the driving member in pressedabutment with the rigid element and simultaneously with the latterapplication to cause pressure fluid to be applied alternately toopposite ends of the hammer piston to reciprocate the latter; and meansresponsive to a predetermined linear movement of the driving membersubsequent to its abutment with the rigid element to shut off flow ofpressure fluid to the machine.

References Cited in the file of this patent UNITED STATES PATENTS963,924 McSherry July 12, 1910 2,546,354 Bacon Mar. 27, 1951 2,648,841Smith Aug. 18, 1953 2,857,596 Allen Oct. 28, 1958

